diff --git a/src/drivers/bus/isa_ids.c b/src/drivers/bus/isa_ids.c
new file mode 100644
index 000000000..f7be1129c
--- /dev/null
+++ b/src/drivers/bus/isa_ids.c
@@ -0,0 +1,24 @@
+#include "etherboot.h"
+#include "isa_ids.h"
+
+/* 
+ * EISA and ISAPnP IDs are actually mildly human readable, though in a
+ * somewhat brain-damaged way.
+ *
+ */
+char * isa_id_string ( uint16_t vendor, uint16_t product ) {
+	static unsigned char buf[7];
+	int i;
+
+	/* Vendor ID is a compressed ASCII string */
+	vendor = htons ( vendor );
+	for ( i = 2 ; i >= 0 ; i-- ) {
+		buf[i] = ( 'A' - 1 + ( vendor & 0x1f ) );
+		vendor >>= 5;
+	}
+	
+	/* Product ID is a 4-digit hex string */
+	sprintf ( &buf[3], "%hx", htons ( product ) );
+
+	return buf;
+}
diff --git a/src/include/isa.h b/src/include/isa.h
index 23a8f2ffa..fe5c557bc 100644
--- a/src/include/isa.h
+++ b/src/include/isa.h
@@ -1,14 +1,10 @@
 #ifndef	ISA_H
 #define ISA_H
 
+#include "isa_ids.h"
+
 struct dev;
 
-#define ISAPNP_VENDOR(a,b,c)	(((((a)-'A'+1)&0x3f)<<2)|\
-				((((b)-'A'+1)&0x18)>>3)|((((b)-'A'+1)&7)<<13)|\
-				((((c)-'A'+1)&0x1f)<<8))
-
-#define	GENERIC_ISAPNP_VENDOR	ISAPNP_VENDOR('P','N','P')
-
 struct isa_driver
 {
 	int type;
diff --git a/src/include/isa_ids.h b/src/include/isa_ids.h
new file mode 100644
index 000000000..0eaa3da12
--- /dev/null
+++ b/src/include/isa_ids.h
@@ -0,0 +1,44 @@
+#ifndef ISA_IDS_H
+#define ISA_IDS_H
+
+/* 
+ * This file defines IDs as used by ISAPnP and EISA devices.  These
+ * IDs have the format:
+ *
+ * vendor  byte 0 bit  7    must be zero
+ *		  bits 6-2  first vendor char in compressed ASCII
+ *		  bits 1-0  second vendor char in compressed ASCII (bits 4-3)
+ *	   byte 1 bits 7-5  second vendor char in compressed ASCII (bits 2-0)
+ *                bits 4-0  third vendor char in compressed ASCII
+ * product byte 0 bits 7-4  first hex digit of product number
+ *		  bits 3-0  second hex digit of product number
+ *	   byte 1 bits 7-4  third hex digit of product number
+ *		  bits 3-0  hex digit of revision level
+ *
+ */
+
+#include "stdint.h"
+
+/*
+ * Construct a vendor ID from three ASCII characters
+ *
+ */
+#define ISA_VENDOR(a,b,c)	(((((a)-'A'+1)&0x3f)<<2)|\
+				((((b)-'A'+1)&0x18)>>3)|((((b)-'A'+1)&7)<<13)|\
+				((((c)-'A'+1)&0x1f)<<8))
+#define ISAPNP_VENDOR(a,b,c)	ISA_VENDOR(a,b,c)
+#define EISA_VENDOR(a,b,c)	ISA_VENDOR(a,b,c)
+
+#define	GENERIC_ISAPNP_VENDOR	ISAPNP_VENDOR('P','N','P')
+
+/*
+ * Extract product ID and revision from combined product field
+ *
+ */
+#define ISA_PROD_ID(product)	( (product) & 0xf0ff )
+#define ISA_PROD_REV(product)	( ( (product) & 0x0f00 ) >> 8 )
+
+/* Functions in isa_ids.c */
+extern char * isa_id_string ( uint16_t vendor, uint16_t product );
+
+#endif /* ISA_IDS_H */
diff --git a/src/include/mca.h b/src/include/mca.h
index f6d37ba79..e69b65601 100644
--- a/src/include/mca.h
+++ b/src/include/mca.h
@@ -19,8 +19,8 @@
 #define MCA_POS_REG(n)			(0x100+(n))
 
 /* Is there a standard that would define this? */
-#include "isa.h"
-#define GENERIC_MCA_VENDOR ISAPNP_VENDOR ( 'M', 'C', 'A' )
+#include "isa_ids.h"
+#define GENERIC_MCA_VENDOR ISA_VENDOR ( 'M', 'C', 'A' )
 
 /*
  * A physical MCA device